1. Field of the Invention
The present invention relates generally to the field of bulk fluid container sensors and, more particularly, to an in-situ container sensor system and method for obtaining real-time temperature and pressure readings used in calculating the actual density of a liquid material in a container.
2. Technical Background
Container sensors are known in the art and typically include capacitance probes, float actuated electro-mechanical devices, hydrostatic (pressure), ultrasonic or manual sensors. These sensors usually provide only the height or level of the liquid material in a container, not the true density of that liquid material at known or various temperatures. Density determinations are in accurate because they are based upon assumptions as to the overall liquid material temperature, and stated specific gravity which may be inaccurate.
In addition to the minimum data acquisition provided by the current container sensors, it is well known that the use of these container sensors provide a safety concern as well. For example, when using a physical measurement system, an individual has to open a hatch on top of the container to use a physical measuring tool, which can not only have environmental concerns but also health and safety concerns. Sensors, such as strain, radar, or ultrasonic, to be used on the exterior of the container to measure the liquid weight or fluid height, e.g., volume of liquid remaining in the tank, appear to solve this concern, however, they only return a single measurement value. Once attached to the exterior of the container, these sensors are difficult to remove or calibrate. Moreover, in instances where two sensors may be used it is difficult to determine the separation distance between the sensors on the outside of the container, due to expansion and contraction of the assembly that holds the two sensors, a slight variation in the distance span between the two sensors could dramatically affect the accuracy of the temperature readings, and thus, the density calculations.
Further, real-time, in-situ density information cannot be provided when using these sensors. For instance, when using an acoustic system, pressure sensors are inserted in the container to measure the volumetric change as a function of the distance to the fluid surface. Thus, use of the current sensors provide no mechanism within which to determine two measurements that indicate actual fluid material inside the container, or the actual steady-state temperature of the material inside the container.
What is needed, therefore, and currently not available in the art, is a sensor that can be inserted into a container to provide real-time measurements of not only the differential pressure exerted by the level of a liquid in a container, but also the temperature of a liquid. In addition, once these measurements are obtained, what is needed is a method by which these measurements are used in the accurate real-time calculation of the density (e.g. specific gravity) of the liquid. Further, the sensor must not only be accurate and easy to use but also provide a means for determining whether leakage (loss of actual level) is occurring from within the container. Additionally, what is further needed is a method of transmitting the data obtained from the container sensor to a data management system to determine real-time density based on differential pressure measurements. It is to the provision of such a container sensor system and method that the present invention is primarily directed.
One aspect of the present invention is to provide a configuration for a container sensor which measures real-time temperature and differential pressure based on two known points in distance.
Another aspect of the present invention relates to a container sensor that can be inserted into the interior of a container to measure at more than one location, the temperature and pressure of the liquid contained therein.
Yet another aspect of the present invention relates to a container sensor that provides not only the height of the liquid in a container, but also the true density (converted to specific gravity) of that liquid based on actual temperature and extrapolated for any temperature.
Yet another aspect of the present invention is to provide a method of using the sensor to determine whether any leakage of the liquid in the container has occurred.
Another aspect of the present invention is to provide a safe and reliable means of measuring the temperature and pressures inside the liquid in a container.
Yet another aspect of the present invention is to provide a method of transmitting the data obtained from the container sensor to a data management system to determine real-time density measurements.
Yet a further aspect of the present invention is to provide a sensor or sensing array that can be easily inserted into the container regardless of the fluid chemistry.
The container sensor invention as disclosed and taught here provides a number of advantages over other container sensors known in the art. For example, having in-situ readings of the temperature and pressure of the liquid inside the container provides greater reliability and accuracy of that data. Since the temperature readings are taken inside the container, the exact liquid pressure (differential pressure between two absolute reference points within the array) and temperature can be determined from the sensors and thus, provide for a more accurate density calculation. In addition, since the container sensor can make several real-time readings of the temperature and pressure at different levels within the liquid, these readings can be used together to determine a more accurate reading. By using the container sensor, one is able to determine whether any leaks exist inside a container, and if so, the flow-rate of those leaks. The container sensor can easily be inserted through a small pipe opening in the container, rather than opening a hatch on top of the container.
These and additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein.